In a UNIX environment, authentication is the process of providing a user identifier (UID) and group identifier (GID) to a user who presents a valid user name and password. In the case of Gateway for NFS, authentication for a Windows user is provided by User Name Mapping.
During authentication, the Windows user name and password are compared with those in the User Name Mapping database. If they correspond with a user name and password in the database, the server returns a corresponding UID and GID. The UID and GID identify the user for NFS browsing and mounting operations.
Without authentication, individual user credentials cannot be established, and Gateway for NFS assigns -2 (anonymous) for both the UID and GID. If the NFS server is configured for anonymous access, you are able to mount and access files. However, anonymous connections are usually limited to read-only operations.
Access to NFS servers is controlled by the Internet Protocol (IP) address of the client. Access to directories and files is controlled by the read, write, and execute privileges granted to various users and groups, who are identified by their UID and GID.